Retroreflective traffic sign and process and apparatus for manufacturing same

Abstract

A method, apparatus for making, and a retroreflective traffic sign consists of a polymeric film having a front face and a rear face, wherein the rear face has a pattern of microprismatic retroreflective elements integrally formed as part of said film; a pattern of cell walls formed of an adhesive-containing polymer defining cells in which the microprismatic retroreflective elements are in the cells; and a substrate is adhered directly to the cell walls formed of the adhesive-containing polymer while leaving an air gap between the microprismatic retroreflective elements and the substrate in the cells.

What is claimed is: 
     
       1. A retroreflective sheet and substrate comprising:
 a polymeric film having a front face and a rear face; 
 said rear face having a pattern of microprismatic retroreflective elements integrally formed as part of said polymeric film, a pattern of cell walls formed of an adhesive, defining cells in which the microprismatic retroreflective elements are in the cells, the polymeric film being provided without any protective backing layer; and 
 a substrate, the substrate adhered directly to the cell walls formed of the adhesive, and leaving an air gap between the rear face and the substrate, the air gap bounded by the pattern of microprismatic retroreflective elements, the cell walls, and the substrate. 
 
     
     
       2. The retroreflective sheet and substrate of  claim 1 , wherein the adhesive has a viscosity of 250,000 cP to 100,000,000 cP. 
     
     
       3. The retroreflective sheet and substrate of  claim 1 , wherein the substrate is selected from aluminum, powder coated steel, galvanized steel, PEEK, polycarbonate, PMMA, recycled tire rubber composites, carbon fiber, fiberglass, and wood composites treated for outdoor use. 
     
     
       4. The retroreflective sheet and substrate of  claim 1 , wherein the microprismatic retroreflective elements include corner cube prisms. 
     
     
       5. The retroreflective sheet and substrate of  claim 1 , wherein the retroreflective sheet meets the requirements of the ASTM D4956-13 standard. 
     
     
       6. The retroreflective sheet and substrate of  claim 1 , wherein the cell walls formed from adhesive are disposed directly on the retroreflective microprismatic elements. 
     
     
       7. The retroreflective sheet and substrate of  claim 1 , wherein the polymeric film is a thermoplastic. 
     
     
       8. The retroreflective sheet and substrate of  claim 1 , wherein the thickness of the cell walls extending from the polymeric film to the substrate is 0.254 mm to 0.508 mm. 
     
     
       9. The retroreflective sheet and substrate of  claim 1 , wherein the polymeric film is 0.127 mm to 0.254 mm in thickness. 
     
     
       10. The retroreflective sheet and substrate of  claim 1 , wherein the front face is an exterior face of the sheet. 
     
     
       11. The retroreflective sheet and substrate of  claim 1 , wherein the front face is at least partly covered with lettering or symbols. 
     
     
       12. The retroreflective sheet and substrate of  claim 1 , wherein the substrate is selected from aluminum, powder coated steel, galvanized steel, PEEK, polycarbonate, PMMA, recycled tire rubber composites, carbon fiber, fiberglass, and wood composites treated for outdoor use. 
     
     
       13. A method for forming a retroreflective sheet and substrate, comprising:
 passing a film having retroreflective elements on one side thereof past a station; 
 at the station, applying to the film an adhesive in a pattern defining cell walls around areas of the retroreflective elements; 
 adhering the film to a substrate by contacting the cell walls to the substrate; and 
 curing the adhesive while the film is adhered to said substrate; 
 wherein the areas of the retroreflective elements, the cell walls, and the substrate define an air gap. 
 
     
     
       14. The method of  claim 13 , wherein the retroreflective elements are integrally formed as part of said film. 
     
     
       15. The method of  claim 13 , wherein the substrate is selected from aluminum, powder coated steel, galvanized steel, PEEK, polycarbonate, PMMA, recycled tire rubber composites, carbon fiber, fiberglass, and wood composites treated for outdoor use. 
     
     
       16. The method of  claim 13 , wherein the retroreflective elements are corner cube prisms. 
     
     
       17. The method of  claim 13 , further comprising applying lettering or symbols to the sheet. 
     
     
       18. The method of  claim 13 , wherein the thickness of the cell walls extending from the film to the substrate is 0.254 mm to 0.508 mm. 
     
     
       19. The method of  claim 13 , wherein the film is 0.127 mm to 0.254 mm in thickness.